Cisco

Cisco Cisco 2901 Password Recovery

Step-by-step password recovery for the Cisco Cisco 2901 (ISR 2900). Console access required.

Overview

This guide provides step-by-step instructions for resetting lost or forgotten administrative passwords on enterprise networking hardware. Follow the procedure below carefully to regain access while preserving your device configuration.

Prerequisites

Before proceeding with password recovery, ensure you have a console cable, terminal emulation software configured to 9600 baud, and physical access to the device.

Step 1: Establish Console Connection

Connect your terminal cable to the console port of the device and open your serial terminal session.

Step 2: Interrupt the Boot Sequence

Power cycle the hardware and issue a Break key sequence during initial system startup to enter ROMMON mode.

Step 3: Reset Password & Configuration

Bypass startup configuration loading, boot into system software, set your new credentials, and save changes back to non-volatile memory.

Overview

This procedure recovers administrator access to the Cisco 2901 when the enable secret or line passwords are lost. The startup configuration is bypassed via the configuration register (confreg 0x2142) and restored afterwards — nothing is erased.

Prerequisites

Console cable (RJ-45 to DB-9 or USB) with a terminal session at 9600 baud, 8N1. Physical or remote power access to reboot the router. The ability to send a break signal from your terminal emulator (Ctrl+Break on PuTTY/Tera Term, Break key on HyperTerminal).

Recovery Procedure — ROMMON Break Method

Connect the console cable and open a terminal session (9600 8N1).
Power-cycle the router (or issue reload if you have limited access).
Within 60 seconds of power-on, send the break sequence (Ctrl+Break) repeatedly until the ROMMON prompt appears: rommon 1>. Timing matters — the break must land during the boot sequence before IOS loads.
Set the configuration register to skip the startup configuration: confreg 0x2142
Boot the router: reset (or boot).
The router boots into IOS with an empty configuration. At the Press RETURN to get started prompt, press Enter.
Enter privileged mode: enable (no password required — config was skipped).
Restore the startup configuration: copy startup-config running-config.
Enter configuration mode: configure terminal.
Set a new enable secret: enable secret <new-password>.
Set line passwords: line vty 0 4 → password <new-password> → login; repeat for line con 0.
Restore the normal configuration register so the router loads its config on future boots: config-register 0x2102.
Exit and save: end, then write memory.
Reboot to verify: reload. Confirm the router boots with the restored config and the new passwords work.

Important Notes

The configuration is not erased — it is bypassed with confreg 0x2142 and restored in step 8. Never skip the config-register 0x2102 step, or the router will keep skipping its config on every boot.
On routers with no break key support, some terminal emulators let you configure a "break" hotkey; alternatively send-break from a Telnet/SSH session with the right line settings can work if you still have login access.
ISR 4000 (4321–4461) and ASR 1000 run IOS-XE but use the same ROMMON break + confreg procedure.
Baud rate is 9600 on these routers — do not use 115200.

Protecting Your Configuration

Before recovery, back up the config: copy running-config tftp://<server>/<filename> or copy startup-config tftp://<server>/<filename>. After recovery, verify show startup-config and show version (confirm configuration register is 0x2102).